Electric switch



1946- G. L. MCFARLAND, JR 94,090

ELECTRIC SWITCH Filed Nov. ll, 1943 i 39 I lllllllllllllmllllilllllllilflllirl 5 P 36 mlmllllllillllllllllllllfllllRIP! nmmlmmmlmmmmuunI GD Inventor: George L.McFa1"|and Jrz,

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Patented Feb. 5, 1946 ELECTRIC SWITCH George L. McFarland, Jr., Scotia, N. Y., assignor to General Electric Company, a corporation of Application November 11, 1943, Serial No. 509,831

New York Claims.

My invention relates to electric switches, more particularly to electromagnetically operated switches of the type known as contactors, and has for its object a simple and reliable electromagnetically operated switch in which provision is made for the detachable mounting of the stationary and movable contacts to provide for the removal of these parts for replacement or repair without disconnecting the external wiring conductors from the terminals of the switch.

My invention is especially applicable to contactors used in the control of electric motors where the space for the contactor is limited and where the shut down time for repair or replacement of the contactor must be made as small as possible. Such an application for which my invention is especially suitable is the operation of electric motor driven machine tools. Thus the contactor having the compact construction of my invention may be located in hidden pockets in the machine tool and, in the event of failure of the contactor, the electric operating parts can be replaced in a very short time, such as a few minutes, after which the operation of the machine tool can be continued.

Another object of my invention is that the stationary and movable switch contacts and the operating magnet therefor are removable from the front of the panel very quickly to provide free access to the electric wiring leading to the switch. The terminal connectors for the external wiring are thus exposed and both hands may be readily used in making the connections both during the original installation of the circuit breaker or later for replacement. Thus the time required for installation of the wiring is reduced to a minimum.

In carrying out my invention in one form I provide a stationary support or base which is secured to the machine tool or other object on which the switch is mounted. This stationary support carries the electric terminal connectors for the switch to which the external electric wiring is connected. I also provide a removable support which is detachably secured to the stationary support'and on which is mounted the switch contacts and the operating magnet for the movable switch contacts.

In one form of my invention I provide butt connection contacts on the two supports, together with positioning means whereby the removable support can be quickly put in place with its butt connection contacts in engagement with the desired cooperating connection contacts on the stationary support. I also provide means for clamping the movable support on the stationary support thereby to press the butt connection contacts in engagement with each other to form reliable electric connections between them.

Moreover, the removable support is provided with barrier walls forming between them are chute chambers, together with one or more cross members extending between the barrier walls on which the stationary switch contacts are mounted so as to be readily accessible after the removable support has been removed from the stationary support.

For a more complete understanding of myinvention reference should be had to the accompanying drawing, Fig. 1 of which is a side elevation view, partly in section, of a contactor embodying my invention; Fig. 2 is a fragmentary front elevation view of the device shown in Fig. 1; Fig. 3 is a. side elevation view to a smaller scale of the stationary base member of the switch; Fig. 4 is a side elevation view of the removable part of the switch; Fig. 5 shows a detail of the movable contact; while Fig. 6 is a perspective view of the removable support.

Referring to the drawing, I have shown my invention in one form as applied to an electromagnetically operated contactor and as comprising two main supporting members made of suitable electrically insulating material such as a moulded compound, i. e. a base supporting plate or stationary support H) which is permanently secured in a substantially vertical position tothe supporting body for the switch, and a removable insulating or arc chute support H which is detachably secured to the base 10. Thus the base has secured to it two securing and guide members l2, only one of which is shown, which are secured to opposite sides of the base and extend perpendicularly outward from the base in parallel relation with each other. Each of these members [2 is channel-shaped with the base of the channel on the outside of the base I0. The sides of the channel members act as guides for projections l3, only one of which is shown, on each side of the removable support I I, these projections being moulded as part of the support. To further improve the horizontal guiding action, the members f2 each have an inwardly extending central groove M which appears as a 4 longitudinal projection on the inside of the memher l2 and fits in a corresponding groove [5 in the projection I3, The support H is assembled on the base Ill by bringing it to the relative position of Fig. 4 with respect to Fig. 3, and then moving it into position against the base 10.

minal connector members 24 are provided each with a rigid bar 26 which is secured to the base by means of a bolt 21 extending through the base. On its outer or upper end this bar carries a terminal screw 28 by means or which an electric wiring conductor can be secured to the bar 26. At its lower end the bar has secured to it in electrically conducting relation a spring contact member 29 which is U-shaped, and the end of which, forming a butt connection contact, is provided with a slot 30 to form two prongs of less rigidity than the remaining portion of the member 29. These prongs facilitate good electrical butt contact with the end of a contact carryme bar 3|, forming a butt connection contact, on the movable support II.

The lower terminal connectors 25 are similar in construction each to the upper member 28, each terminal 25 being provided with a connection screw 32 on its lower end and with an inverted U-shaped spring connector 33 on its upper end. The end of this spring member 33 forms a butt connection contact and cooperates with a contact carrying bar 34, forming a butt connection contact, on the movable support I I.

For convenience in assembly, the series of upper terminals 24 are mounted each on a slightly raised portion on the face of the base It), as shown clearly in Fig. 1, and the walls l923 on each side of the terminals are considerably higher to provide better mechanical separation of the ends or conductors secured to the terminals by the screws 28.

On the lower end of the base 10 are two more terminal connectors 35 and 38 similar in construction to the terminal connectors 25 and in such a position that their spring butt connection contacts 31, only one of which is shown, are engaged by spring butt connector contacts 38, only one oi which is shown, carried by the operating coil 39 and to which the ends of the coil winding are connected.

Th removable or detachable are chute support H comprises, in eflect, a plurality of parallel imperforate barrier walls 49, Fig. 6, which walls are complementary with the partition walls l9--23 on the base l and when the support II is secured on the base engage the outer ends or edges of the partition walls in abutting relation therewith. Thus in the device shown, with four pairs of stationary terminal connectors 24, 25 and five partition walls i9-23, the support II has five parallel walls 40. These walls are joined together by the relatively heavy wall 4| on the front 01 the support or the right-hand side, as seen in Fig. 1, and also by two cross members 42 and 43. It will be understood that the two outermost plates 48 have on their exterior the guiding and securing projections l3. The support H with its walls and connecting portions 4|, 42, and 43 is moulded as a single piece from a suitable electrically insulating compound, such as a phenolic condensation product.

The cross member 42 forms a support for the contact carrying bar 3| which is secured to it by a suitable screw 44. At its right-hand end, as seen in Fig. 1, the bar 3| has a downwardly extending portion to which is secured by a screw 45 and L-shaped member 45 carrying on its lower end a stationary switch contact 41. The bar 34 is somewhat similar in shape to the bar 48. It is secured at its lower end by a screw 48 to the cross bar 43. Its upper end is bent over toward the right and carries on its lower side a stationary switch contact 49. Thus it will be understood that inthe device shown tour compartments or chambers are provided in each of which is mounted a pair of stationary switch contacts 41 and 49, a shown in Fig. l.

Cooperating with each pair of stationary switch contacts is a bridging switch contact member 56. only one of which is shown. Each bridging contact is in the form of a strip with a switch contact on each end. The strip is mounted between the sides of a U-shaped supporting part 51, Fig. 5, and pressed upward by a spring 52 against proleotions 53 on each side of the U-shaped member, the bridging member being provided with corresponding projections which engage the pro jections 53. These bridging contact supporting members 5| are in turn secured as by suitable screws to a cross member 54 made of electrically insulating material which extends across the base l9 and is mounted on the upper end of the plunger armature 55 of the coil 39.

The stationary core member 56 of the magnet is secured to a metal front plate member 51 having a pair of projecting arms 58, only one of which is shown, to which the core member 55 and the coil 39 are secured directly. This plate is in turn secured to the insulating support H by screws 59 and 69 at intervals.

Also mounted on the base at its lower end on opposite sides are two thermal current responsive overload protective devices GI and 62, shown as of the construction described and claimed in U. S. Patent No. 2,168,180, issued on August 1, 1939 to George R. Townsend. Each of the devices is provided with electric terminals 63 and 64 by means of which it can be connected in an electric circuit with a selected one of the switches.

Thus it will be observed that the stationary support [9 may be secured to the body on which the contactor is mounted, such as a machine tool, and the external wiring connections made to the terminal connectors mounted on the front of the stationary support. Since the terminal connectors are all mounted on the front of the stationary support or base, they are obviously readily accessible for making the connections with the external wiring even though the contactor is mounted in the smallest possible space. After the wiring connections have been thus made, only the very simple operation remains of putting the removable support H in place and securing it. The removable arc chute support is simply elevated to a position in alignment with the stationary support and then moved toward the stationary support so that the projections l3 enter the channel shaped guide members l2 whereby the removable support is guided horizontally into a position such that each butt connection contact on the removable support engages its cooperating connection contact on the stationary support. Then the screws l6 and I! are screwed into the holes provided for them on the ends of the guides l2 thereby to clamp the removable support to the stationary support. For removal, the screws are disengaged and the arc chute support is then simply drawn out horizontally.

This securing and clamping means consistin of the screws is an important feature of my in-' vention for the reason that the screws provide a very simple and effective means for applying a very substantial force to the removable support in clamping it against the stationary support. It will be understood that with a plurality oi sprin mounted butt connection contacts on either the stationary support, as shown, or on the removable support, a very considerable clamping force must be applied in order to cause depression of the spring connection cont-acts thereby to produce a wiping action and form an efilcient electric contact. Also, this arrangement of butt connection contacts and clamping screws provides for the greatest ease in the separation oi. the connection contacts. In comparison, it will be understood that if an equal number of sliding plug contacts were provided, a very considerable force would be required on the part of the service man or operator in forcing the removable support into position against the friction of a plurality of connection contacts, as well as in removing the removable support against this friction.

Another advantage of the butt connection contacts is that they provide for a reasonable amount of tolerance in the positioning of the removable support on the stationary support.

It will be observed that each pair of stationary contacts and their cooperating bridging contact are mounted in a vertically extending arc chute chamber or duct formed between adjacent barrier walls, the supporting plate It! at the back, and the cross plate 4| at the front.

After the removable support has been removed, it will be observed that the screws 44 and 48 are accessible for removal of the stationary switch contacts for repairs or replacement, if necessary. Of course, the important advanta e is that a replacement removable support with its switch contacts and operating magnet can be kept available for immediate installation and continuance of service, while repairs can be made on the defective switch mechanism later on as convenient.

Another feature of my invention is the construction of the contact carrying bars or members 34 and 46 in such a manner that they can be interchanged to provide a normally closed switch. Thus the bars each have one end secured respectively to the cross members 42 and 43 by means of the screws 45 and 48. The bar 34 extends upward from its screw 48 and the bar 46 extends downward from the screw 45 in substantiall parallel relation with the bar 34, On their opposite upper and lower ends respectively the bars have portions bent laterally toward each other and lying in substantially the same plane, the contacts 41 and 49 being, as shown in Fig. 1, on the lower sides of these laterally extending portions and the contact surfaces of the contacts being in substantially the same plane, Furthermore. the contacting surfaces of the contacts 41 and 49 are equal distances from the centers of their respective clamping screws 45 and 48. Also, the bars are each shaped to engage the contact 33 when the bar is mounted on the cross member 43.

The bars 34 and 46 are interchanged by simpl detaching them by means of the screws 48 and 45, and then mounting them in their interchanged positions in which the contact surfaces of the contacts are substantially in the same plane as before, although the contacts will then be on the upper sides of the laterall extending portions of the bars instead of on the lower sides, as seen in Fig. 1. Also, to provide a normally closed switch, the bridging contact member 50 is removed from the U-sh-aped bracket member reversed and mounted on top of the shoulders 53 with the spring 52 extending upward between the bridging member 52 and a seat or depression 65 for its upper end in the cross member 42.

With the coil deenergized, the bridging member 50 and its contacts, in this reversed position,

rests on the stationary contacts and is biased downward against the contacts by the spring 52. When the armature 54 is picked up by the coil, the shoulders 53 engage the bridging contact 50 and lift it to its open circuit position.

It will be observed that the sides of the U-shaped member 5| guide the bridging member 50. I contemplate that the cross member 54 will be positioned accurately by the plunger armature 55 whose dimension tolerances in its guide inside the coil 39 will be close so that the U-shaped support 5| and the bridging member 50 will move between the walls 48 without engaging them whereby wear is prevented.

I have also provided a special arrangement of the screws l5 and H for securing them to the front plate member 51. As shown in Fig. 4, each screw is provided with an unthreaded portion 66 of reduced diameter between the knurled head of the screw and the threaded portion of the screw. Thus the screw is turned through the threaded hole in the plate member 51 until the portion 65 of reduced diameter extends loosely through the threaded hole, A look washer 61 preferably is provided between the knurled head and the plate member.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not with to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising a stationary supporting plate made 06 electrically insulating material arranged to be mounted in a substantially vertical position, a plurality of terminal connectors secured to said supporting plate, quickly detachable connection contacts connected to said terminal connectors, a removable support made of electrically insulating material provided with a pluralit of barrier walls forming between them a plurality of arc chambers, cross connecting means extending between each of said barriers and its next adjacent barrier, a pair of stationary contacts in each of said are chambers mounted on said cross connecting means, quickly detachable connection contacts connected to said stationary contacts positioned between said barrier walls adjacent one side of said removable support, cooperating positioning means on said stationary support and said removable support for positioning said removable support for horizontal sliding movement to bring said side against said supporting plate with said parallel walls extending vertically and said connection contacts on said removable support in engagement with said connection contacts on said supporting plate, means for detachably securing said removable support in said position on said supporting plate, operating means mounted on one of said *upports, and bridging contacts in said chambers movable by said operating means into engaging and disengaging relation with said pairs of stationary contacts.

2. An electric switch comprising a supporting plate made of electrically insulating material arranged to be mounted in a substantially vertical position, upper and lower rows of terminal connectors secured to said supporting plate, upper and lower rows of quickly detachable spring butt contacts connected to the terminal connectors of said rows, a removable support, a pluralit of pairs of stationary switch contacts m'ountedon said removable" support; two rows 01 butt connection :contacts on said removable support for engagement respectively with said two rows of spring contacts on said supporting plate, electric connections between the stationary switch contacts oi each pair and a pair of butt connection contacts in said rows respectively, an operating coil mounted on said removable support, an armature ior said coil, an insulating cross member secured to said armature, a plurality of bridging contact members mounted resiliently on said cross member cooperating respectively with said pairs of stationary contacts, a pair of spring butt contacts for said operating coil mounted on said stationary support, quickly detachable terminal connectors secured to said coil contacts, butt connection contacts for said operating coil secured to said operating coil for cooperation with said operating coil contacts on said supporting plate, cooperating guide means on said supporting plate and said removable support tor positioning said removable support tor horizontal sliding movement to bring said butt connection contacts on said removable support into engagement with said butt contacts on said supporting plate when said removable support is moved into a predetermined position in engagement with said supporting plate determined by said guide means, and means for detachably securing said removable support on said supporting plate.

3. An electric switch-comprising a supporting plate made of electrically insulating material arranged to be mounted in a substantially vertical position, a plurality of terminal'connectors secured to said stationary support, quickly detachable connection contacts connected to said terminal connectors, a removable support made of electrically insulating material comprising a plurality of parallel walls forming between them a plurality 01' are chambers, at least two cross members connecting each or said walls to its next adjacent wall, a common cross member made of electrically insulating material integral with the ends 01' said walls forming an imperforate side wall of saidremovable support, a pair 01 stationary contacts in each oi! said are chambers mounted on said cross members, connection contacts for said stationary contacts positioned adlacent an open side of said removable support opposite said imperiorate side, cooperating guide means onsald supporting plate and said removor terminaLconnectors mounted on saidsupports ingfplatesin vertically spaced relation with each other between said barrier walls, said terminal connectors being provided with first quickly detachable connection contacts, a removable arc chute member made of electrically insulating material comprising a pair of second parallel arc barrier walls joined together on one side by an integral imperiorate front wall, said second barrier walls being spaced apart the same distance assaid first barrier walls and having their edges opposite said front wall arranged to fit in a predetermined position in abutting vertically extending edgewise relation on said first barrier walls, a pair 01' stationary contacts mounted on said are chute member between said second barrier walls, second quickly detachable contacts connected to said stationary contacts in position to engage said first detachable contacts on said supporting plate when said arc chute member is mounted in'said predetermined position on said supporting plate with said barrier walls in abutting relation with each other to form a verticall y extending arc chamber duct in which said stationary contacts are mounted, means for detachably-securing said are chute member in said position on said supporting plate, and a bridging contact-member movable mounted on said aro chute" member in said are chamber duct tor cooperation with, said stationary contacts.

-5.. An electric switch comprising: a supporting platemade of electrically insulating material as able support for positioningsaid removable support for horizontal sliding movementto bring said open side against said supporting plate with said parallel walls extending vertically and said connection contacts on said removable support in engagement with said connection contacts on said supporting plate, means for detachably securing said removable support insald position on said supporting plate, operating means mounted on said removable support, a cross member con- 'zected to said operating means extending across a second open side 01' said removable support, and bridging contacts in said chambers cooperating with said stationary contacts mounted on said cross member. v

4. An electric switch comprising a supporting plate made oi electrically insulating material arranged to be moimted in a substantially vertical position, a pair or first are chute barrier walls on said supporting plate extending vertically in parallel spaced relation with each other, a pair ranged to be mounted ina substantially vertical position, *a 'pluralitroi first" arc.chute barrier walls; on said: supporting plate: extending 'verticaily in parallel'spacedrelation with each other. a pair of terminalconnectors-mounted on said supporting plate in vertically spaced relation with each other between said barrier walls, said terminal connectors being provided with first quickly detachable connection contacts, a removable arc chutev member made of electrically insulating material comprising a plurality oi second parallel arc barrier walls joined together on one side by an integral imperforate front wall, said second barrier walls being spaced apart the same distance-as said first barrier walls and having edges opposite'said front wallarrangedto fit in a predetermined position in abutting vertically extending edgewise relation on said;;first barrier walls, at least two cross members extending between said' second barrier walls, a stationary switch contact mounted on each or said cross members, second quickly detachable contacts on said cross members connected to said stationary contacts in position to engage said first detachable contacts on said supporting plate when said arc chute member is mounted in said predetermined position on said supporting plate, cooperatingguide means on said supporting plate and said are chute member for positioning said are chute member rior horizontal sliding movement to said'predetermined position with said barrier walls in abutting relation with each other to iorr'n:avertically extending arc chamber duct, means for detachably securing said arc chute member in said position on said supporting plate, a bridging contact member movably mounted on said arc chute member in said arc chamber duct ior c'ooperation with said stationary contacts, and operating means for saidv bridging contact member mounted on said arc chute member.

. GEORGE L, McFARIAND, JR. 

